DNA damage, somatic aneuploidy, and malignant sarcoma susceptibility in muscular dystrophies

Area of Science:

• Oncology
• Genetics
• Muscle Biology

Background:

• Muscular dystrophies (MDs) are genetically diverse but share muscle wasting and tissue changes, suggesting a common underlying mechanism.
• Previous research has not fully elucidated the link between MDs and tumor development.

Purpose of the Study:

• To investigate the potential for spontaneous tumor formation in mouse models with mutations in key muscular dystrophy genes.
• To identify common molecular and genomic alterations in MD-associated tumors and compare them to human MD patient tissues.

Main Methods:

• Generated mouse models with mutations in Dmd, Dysf, Capn3, and Large genes.
• Analyzed tumor histology, incidence, latency, and localization.
• Performed genomic analysis of MD sarcomas, including copy number alterations and DNA damage assessment.
• Examined skeletal muscle from human MD patients for genomic instability.

Main Results:

• Mutations in MD genes led to spontaneous skeletal muscle sarcomas (rhabdomyo-, fibro-, and liposarcomas) in mice.
• Specific gene combinations (e.g., dystrophin/dysferlin loss) accelerated tumor formation.
• MD sarcomas exhibited non-random genomic alterations, including tumor suppressor loss, oncogene amplification, and chromosomal duplications.
• Genomic instability, DNA damage, and aneusomies were present in aged MD mouse muscle and human MD patient muscle prior to or independent of tumor formation.

Conclusions:

• MDs can predispose to skeletal muscle sarcoma development through shared pathomechanisms.
• Genomic instability is a common feature in both MDs and associated tumors, affecting both mouse models and human patients.
• These findings suggest novel therapeutic strategies targeting common molecular pathways in MDs and cancer.